From the beginning I had bronchoscopies done, rather than coughing, for the same reasons mentioned. Neither of the bronchs provided positive cultures. The second one resulted in a 30% lung collapse. My new pulmonologist suggested we try getting an induced sample. I did three on separate days, and within two weeks had cultured positive for mai. Maybe you are familiar with this already, but I breathed saline vapor with a device attached to implement bringing up sputum. I never felt the need to cough, but after quite awhile I forced myself to cough from my toes up, as hard as I could. I did another one yesterday, and the rt seemed a little impatient with me, but I really didn’t care. Breathing that saline as long as possible helps liquify the mucous. I think maybe some of us have thick mucous, the same problem cf patients have. I also clear my throat a lot, but rarely feel the urge to cough.